What process is indicated by an increase in fluorescence in the presence of DPC?

The correct answer is that DPC exposes hydrophobic residues. In biochemical assays, fluorescence can be used to monitor conformational changes in proteins. When DPC (a chemical denaturant) is added to a protein solution, it can disrupt the protein's native structure, leading to the exposure of hydrophobic regions that are typically buried within the folded state of the protein.

In native proteins, these hydrophobic residues are often shielded from the aqueous environment, contributing to the overall stability of the protein's structure. When the protein unfolds or changes conformation due to the influence of DPC, these hydrophobic regions become accessible, leading to increased fluorescence. This fluorescence increase is indicative of an alteration in the environment of these hydrophobic residues, suggesting a conformational change in the protein's structure that exposes these previously hidden areas.

This mechanism is commonly utilized in various biochemical applications to study protein folding, interactions, and stability under different conditions.